Hi Jerome,
For an IDES system I suppose it doesn't really matter license / cost wise ... if that is the case then you can simply use your own user and set that one as standard logon user for the services you want to test ... ( via transaction SICF ) ... You shouldn't be doing that ofcourse for a productive system ... There you would typically create a service user type ( SU01 ) or for some web applications you could use internet users ( SU05 ).
Steven